UNIVERSITY    OF    CALIFORNIA     AGRICULTURAL   EXPERIMENT  STATION 

BENJ.    IDE    WHEELER,    PRESIDENT 

THOMAS    FORSYTH    HUNT,    DEAN  AND  DIRECTOR 

BERKELEY  h.  e.  van  nornian,  vice-director  and  dean 

University  Farm  School 


COLLEGE   OF  AGRICULTURE 


CIRCULAR  No.  177 

October,  1917 


GRAIN   SORGHUM  SEED 


By  EENEST  B.  BABCOCK 


Fig.  1. — Dwarf  milo;  right,  an  excellent  head — erect,  compact,  well-filled;  left,  a 
poor  head — crook-necked  and  loose  although  large  and  well-filled. 


The  grain  sorghums  as  commonly  grown  in  California  are  exceed- 
ingly variable.  This  is  especially  marked  in  the  case  of  Milo,  which 
is  the  most  extensively  cultivated  variety.  For  example,  most  fields 
of  Milo  consist  of  a  mixture  of  tall,  medium,  and  short  plants,  and 
such  fields  cannot  be  harvested  by  machinery.  In  order  to  harvest 
with  a  header  it  is  necessary  that  the  field  be  fairly  uniform  in  height. 
The  plants  in  an  ordinary  field  of  grain  sorghum  also  differ  greatly 
in  yield,  some  producing  a  single,  large,  well  filled  head,  while  others 
bear  two  or  more  small  or  poorly  filled  heads.  The  maximum  yield 
will  be  obtained  by  growing  the  largest  practicable  number  of  single- 
stalked  plants  and  the  crop  can  be  harvested  most  economically  if 
the  plants  are  of  uniform,  medium  height. 

The  cost  of  selecting  better  seed  is  very  small,  but  the  results  of 
growing  crops  from  such  seed  may  be  surprisingly  valuable.  The 
actual  work  of  seed  selection  can  be  done  by  boys  if  necessary,  as  has 
been  demonstrated  by  the  boys'  clubs  (see  fig.  2).  Success  with 
seed  selection  depends  upon  knowing  how.  It  is  the  purpose  of  this 
circular  to  present  simple,  definite  directions  for  selection  of  grain 
sorghum  seed.  In  order  that  the  reasons  for  these  directions  may 
be  understood,  the  principles  and  methods  of  seed  selection  will  be 
briefly  discussed. 

PRINCIPLES    AND    METHODS 

Selection  will  bring  results  with  any  crop,  but  the  results  obtained 
will  depend  mainly  on  two  factors ;  first,  the  manner  of  reproduction 
in  each  kind  of  plant;  second,  the  method  of  selection  used.  As  re- 
gards the  first  factor,  plants  are  either  self -fertilized,  in  which  case 
the  male  and  female  elements  come  from  the  same  plant  or  even  the 
same  flower,  or  they  are  cross-fertilized,  in  which  case  the  male  and 
female  elements  come  from  two  plants.  Wheat,  barley,  rice,  and 
beans  are  described  as  close-fertilized,  which  means  they  are  not  only 
self -fertilized,  but  that  each  flower  fertilizes  itself.  Only  rarely  do 
the  flowers  on  these  plants  open  in  such  a  way  as  to  permit  of  crossing 
with  other  plants.  Therefore,  as  commercial  varieties  contain  plants 
which  differ  inherently,  it  is  possible  to  isolate  different  strains  from 
such  varieties'  by  the  single  act  of  gathering  seed  from  individual 
plants,  provided  the  seed  from  each  plant  is  sown  separately.  In 
sorghum,  corn,  cotton,  and  melons,  however,  this  cannot  be  done  so 
easily,  for  these  plants  are  naturally  cross-fertilized  to  a  greater  of 
less  extent,  and  the  seed  from  a  single  plant  under  field  conditions  is 
more  or  less  likely  to  be  of  mixed  ancestry,  and  hence  to  produce 
mixed  progeny.  For  this  reason,  as  a  general  rule,  different  varieties 
of  these  and  other  cross-fertilized  plants  intended  for  use  as  seed 
should  not  be  planted  near  each  other.  The  result  of  such  planting 
is  an  undesirable  mixture  difficult  to  handle  satisfactorily  and  often 
less  productive  than  either  parent.  The  important  factor  determin- 
ing the  effectiveness  of  seed  selection  is  the  method  used.  For  the 
present  emergency  there  are  three  practicable  methods:  (1)  the  choos- 
ing of  good  fields  for  seed;  (2)  roguing  seed  fields;  (3)  selecting  the 
host  plants  for  next  year's  seed.      These  methods  will  be  considered 


with  special  reference  to  grain  sorghums.     The  following  remarks  are 
by  way  of  introduction. 

1.  Many  of  the  "standard"  varieties  of  sorghum  have  become 
badly  mixed.  This  reduces  the  uniformity  of  the  crop  and  may 
decrease  the  yield.  Another  important  consideration  is  the  fact  that 
localities  differ  more  or  less  in  soil  and  climate,  and  in  each  commer- 
cial variety  there  may  be  strains  which  are  better  adapted  to  your 
locality  than  are  other  strains  of  the  same  variety.  This  will  cer- 
tainly be  found  in  the  case  of  such  strikingly  different  regions  as  the 
Imperial  Valley  and  the  northern  coast  counties,  but  it  also  holds 
for  less  distinct  localities.  This  is  a  good  reason  for  encouraging  seed 
selection  in  every  agricultural  district  of  the  state.      Of  equal  im- 


Fig.  2. — By  the  selection  of  heads  of  uniform  height  and  of  the  desired  type, 
in  the  field  before  harvest,  for  two  years,  this  boy  secured  this  uniform  field  of 
dwarf  milo  the  third  year.  The  yield  is  estimated  at  5000  pounds  of  grain  per 
acre,  while  the  present  average  yield  per  acre  for  California  is  1800  pounds. 


portance  is  the  use  of  well  cleaned  and  carefully  graded  seed.  The 
practical  value  of  planting  large,  plump  seeds,  free  of  weeds,  is  very 
great.  It  must  be  admitted  that  the  finest  fields  of  a  given  variety 
are  usually  owned  by  those  who  practice  the  best  methods  of  culture 
or  who  are  specially  fortunate  as  regards  soil,  time  of  planting,  etc. 
Hence  in  selecting  the  finest  single  field  in  a  certain  locality  for  seed 
we  do  not  know  that  this  seed  is  inherently  superior  to  seed  from 
neighboring  fields.  It  is  a  safe  risk,  however,  to  assume  that  it  is 
equally  good  and  there  are  some  chances  that  the  best  fields  contain 
a  large  proportion  of  superior  strains.  Production  in  1918,  therefore, 
can  be  increased  by  choosing  superior  fields  of  single  varieties  and 
giving  special  attention  to  cleaning  and  preserving  the  seed.  Con- 
siderable care  should  be  given  to  selecting  such  fields. 

2.  'Roguing  is  a  supplementary  effort,  tn   insure  the   purity  and 


uniformity  of  the  variety.  It  consists  in  pulling  or  chopping  all 
plants  of  other  varieties  or  types  so  as  to  reduce  contamination  of 
the  stock.  As  practiced  by  progressive  seed  growers  it  is  an  indis- 
pensable part  of  the  programme  followed  in  producing  high  grade 
seed.  In  this  work  not  only  are  plants  of  other  varieties  eliminated 
but  a  definite  type  is  maintained  so  far  as  practicable.  Even  if  no 
roguing  can  be  done  this  year,  the  careful  selection  of  fields  for  the 
local  supply  of  next  year's  seed  is  urged  upon  every  farming  com- 
munity and  agricultural  organization  in  the  state. 

3.  The  other  method  will  probably  appeal  most  to  individual 
growers,  although  there  is  no  reason  why  it  should  not  become  part 
of  a  community  project,  provided  the  work  is  put  in  charge  of  re- 


Fig.  3. — This  boy  selected  heads  of  grain  for  seed  after  the  entire  crop  had 
been  harvested  and  thrown  in  a  pile.  Note  the  nonuniforrnity  in  the  height  of 
the  heads.  To  harvest  this  field  will  require  almost  as  much  time  as  will  be 
required  for  the  properly  selected  field,  although  the  yield  will  be  only  slightly 
above  average. 

sponsible  parties.  Selecting  the  best  plants  for  bulk  seed  can  be 
done  easily  by  any  grower  if  he  will  confine  his  attention  to  a  very 
few  essential  points.  The  first  consideration  will  usually  be  yield, 
but  often  there  is  some  other  point  equally  important;  for  example, 
in  sorghum  it  is  height  of  plant ;  in  cotton,  length  of  staple ;  in  pota- 
toes, number  of  marketable  tubers,  etc.  By  going  through  the  field 
before  harvesting,  seed  for  the  next  crop  can  be  gathered  from  selected 
plants  with  but  little  extra  trouble.  The  results  secured  will  usually 
repay  for  this  trouble  many  times  over. 

FIELD    SELECTION 

Choosing  Seed  Fields. — There  are  several  distinct  kinds  of  grain 
sorghums  and  they  cross  readily  with  each  other.  For  this  reason 
some  fields  of  sorghum  are  so  much  mixed  that  it  is  hardly  worth 


while  to  practice  seed  selection.  On  the  other  hand,  some  growers 
have  already  practiced  selection  of  sorghum  seed  and  efforts  should 
be  made  to  locate  such  sources  of  superior  seed.  Farm  Bureaus  and 
other  agencies  looking  for  stocks  of  grain  sorghum  seed  should  con- 
sider only  fields  composed  of  a  single  variety.  As  a  rule  it  is  wise 
to  choose  the  variety  that  has  proven  most  successful  locally.  Starting 
with  such  a  field,  provided  it  is  separated  by  a  distance  of  100  yards 
or  more  from  other  varieties,  there  is  no  question  that  selected  and 
graded  seed  will  give  much  better  results  than  the  unselected  crop 
from  the  same  field. 


Fig.  4. — Dwarf  milo ;  right,  an  ideal  plant — medium  height,  single  stalk,  no 
rattoons,  head  erect,  free  from  boot,  compact  and  well-filled;  left,  a  very  poor 
plant — too  tall,  with  suckers  and  rattoons,  crook-necked. 


Selecting  Seed  from  Chosen  Fields. — Seed  for  the  1918  crop  should 
be  gathered  before  the  main  crop  is  harvested.  This  can  be  done  by 
driving  a  double  wagon  (or  a  single  horse  and  sled)  up  and  down 
the  field  while  several  men  or  boys,  each  working  on  one  or  two  rows, 
select  and  cut  the  heads  and  throw  them  into  the  wagon.  These  men 
should  be  given  definite  instructions  according  to  the  variety.  In 
general  aim  at  two  things,  viz.,  high  yield  and  uniform  height.  To 
get  high  yield  pick  the  largest,  most  compact,  well  filled  heads.  An 
excellent  plant  of  dwarf  milo  is  shown  on  the  right  in  fig.  4  and,  on  the 
left,  a  plant  which  is  undesirable  in  every  feature.  An  ideal  head 
and  a  very  poor  head  are  shown  in  fig.  1.  To  get  more  uniformity  in 
height  select  only  from  plants  of  medium  growth,  avoiding  both  the 
very  short  and  very  tall  plants.  Any  workman  of  ordinary  intelli- 
gence can  follow  these  directions  and  there  is  no  question  that  seed 
selected  according  to  this  simple  plan  will  produce  better  results  than 


6 

ordinary  unselected  seed.  The  greater  the  care  used  in  selecting 
individual  plants  the  more  valuable  the  results,  provided  proper 
standards  are  observed.  The  following  score  card  prepared  by 
Hendry  gives  definite  directions  regarding  each  of  the  important 
points  to  be  considered. 

Score  Card  for  Grain  Sorghums 

Perfect   score 

1.  Earliness    15 

2.  Erectness   of   head 5 

3.  Size,  weight,  and  compactness  of  head 20 

4.  Freedom  of  head  from  boot 5 

5.  Freedom  from  suckers  or  branches 5 

6.  Besistance   to   lodging 5 

7.  Height    of    stalk 5 

8.  Firmness    of    stalk 5 

9.  Juiciness    of    stalk 5 

10.  Abundance  of  leaves 10 

11.  Greenness  of  leaves  late  in  season 5 

12.  Purity  15 

Total  100 

Explanation  of  Terms 

1.  Earliness. — Early  maturity  means  drouth  evasion.  Under  middle  Sacra- 
mento Valley  conditions  the  Duras  should  ripen  in  from  90  to  110  days. 

2.  Erectness  of  Head. — Goose-necks  interfere  with  machine  harvesting,  shock- 
ing, and  feeding,  and  should  be  discriminated  against.  If  slightly  inclined  or 
nodding,  cut  less  severely. 

3.  Size,  Weight,  and  Compactness  of  Head. — Large,  well  filled  heads  mean 
large  yields  and  this  point  should  be  given  precedence  over  all  other  characters, 
a  good  head  with  a  two-inch  stem  should  consist  of  85  per  cent  grain  by  weight. 

4.  Freedom  of  Head  from  Boot. — Heads  which  do  not  clear  the  boot  completely 
do  not  mature  uniformly,  are  apt  to  be  off  color,  and  damaged  by  insects. 

5.  Freedom  from  Suckers  or  Branches. — Plants  which  are  free  from  suckers 
and  lateral  branches  (or  rattoons),  are  more  uniform  in  height  and  ripening,  and 
are  therefore  more  desirable. 

6.  Resistance  to  Lodging. — Even  though  a  plant  is  good  in  other  respects,  if 
it  shows  a  tendency  to  lodge  it  should  not  be  selected  for  seed. 

7.  Height  of  Static. — Excessive  height  makes  cutting  by  hand  difficult  and 
heading  by  machinery  almost  impossible.  Plants  of  short  stature  also  have  lower 
water  requirements. 

8  and  9.  Fineness  and  Succulence  of  Stalk. — Small  juicy  stalks  are  preferable 
to  coarse,  pithy  ones  and  should  be  given  preference  in  selection. 

10  and  11.  Abundance  of  leaves,  especially  if  they  retain  their  greenness  and 
succulence  late  in  the  season,  is  a  factor  in  determining  the  fodder  value  of  the 
plant. 

12.  Purity. — Sweet  sorghum,  broom  corn,  and  Sudan  grass  mix  readily,  and 
1  lie  hybrid  plants  can  usually  be  distinguished  by  their  vigor,  coarseness,  or  late 
maturity.      Since  they  do  not  breed  true  they  should  not  be  selected  for  seed. 

Preserving  the  Seed. — Dry  the  selected  heads  on  trays,  turning 
from  tray  to  tray  every  three  or  four  days ;  or  spread  on  the  ground 
and  turn  with  a  fork  if  necessary  to  insure  thorough  drying.  This 
drying  is  absolutely  essential  as  heating  is  certain  to  occur  when  the 
leads  are  stored  while  still  moist.      When  thoroughly  dry  the  heads 


may  be  preserved  by  placing  them,  loosely  in  grain  sacks  and  hanging 
the  sacks  in  a  dry  place.  By  suspending  the  sacks  with  wire  the  Joss 
from  mice  will  be  reduced.  If  necessary  the  heads  can  be  threshed 
at  once  and  stored  in  a  dry  place,  but  if  this  is  done  the  individual 
heads  cannot  be  tested  for  germination.  It  is  better  to  thresh  by 
hand  as  there  is  less  danger  of  injuring  the  seed  in  such  a  way  as  to 
prevent  germination. 

Testing  for  Germinating  Poiver. — It  is  important  to  know  that  the 
seed  to  be  planted  will  germinate  well.  Some  heads  produce  seed  of 
lower  germinating  power  and  the  use  of  such  seed  causes  poor  stands 
of  sorghum.  By  using  seed  known  by  test  to  have  germinating  power 
less  seed  per  acre  will  be  needed  to  insure  a  good  stand  than  with 


Fig.  5. — Good  yields  of  grain  can  not  be  secured  when  the  crop  is  planted  too 
thickly  and  sufficient  moisture  is  not  available.  The  above  picture  illustrates  the 
interplanting  of  five  rows  of  grain  between  trees  in  a  young  orchard.  The  two 
outside  rows  gave  a  fair  crop  of  heads,  while  the  center  row  did  not  give  a 
single  head,  and  the  two  intermediate  rows  only  a  few  heads.  More  grain  would 
have  been  secured  had  only  three  rows  been  planted,  or  the  five  rows  thinned  out 
considerably. 

unselected  seed.  A  simple  method  of  testing  is  to  fill  a  box  nearly 
full  of  thoroughly  moist  soil  or  sand,  level  the  surface,  and  mark  it 
off  into  squares  about  two  inches  in  diameter.  Mark  one  corner  so 
it  will  be  possible  to  count  in  regular  order  to  any  check.  In  each 
square  punch  nine  holes  about  half  an  inch  deep,  three  rows  of  three 
holes  each,  near  the  center  of  the  square.  Lay  out  the  heads  to  be 
tested  in  a  row  where  they  will  not  be  disturbed  for  a  few  days.  Start- 
ing at  one  end  of  the  row  take  up  each  head  in  order  and  pick  off 
nine  kernels  from  different  parts  of  the  head.  Place  these  in  the  nine 
holes  in  square  No.  1  and  cover  firmly  with  soil.  After  kernels  from 
each  head  have  been  planted  set  the  box  in  a  warm  place.  The  seed 
should  sprout  in  a  few  days  if  kept  sufficiently  warm.      No  heads 


8 


should  be  used  that  give  less  than  seven  sprouted  seeds.      Heads 
producing  weak  or  sickly  seedlings  should  be  discarded. 

Boguing  the  Field. — In  fields  that  have  not  yet  headed  out  it  will 
pay  to  rogue  the  field,  or  that  portion  of  it  from  which  seed  is  to  be 
selected.  This  should  be  done  about  a  week  before  the  earliest  plants 
begin  to  bloom.  The  object  of  roguing  is  to  remove  all  off -type  plants 
so  as  to  prevent  the  crossing  of  these  plants  with  the  plants  to  be 
selected  later.  At  this  stage  plants  that  are  too  tall  can  be  detected 
as  easily  as  when  the  crop  is  mature,  also  weak  or  diseased  plants,  etc. 
If  it  is  too  late  to  rogue  this  year,  it  should  become  the  preliminary 
step  to  seed  selection  in  1918  and  succeeding  years. 


Fig.  6. — The  desirable  heads  may  be  cut  before  harvest  and  thrown  into  a  wagon 
driven  through  the  field.     About  twelve  heads  of  grain  will  plant  an  acre. 


TESTING     INDIVIDUAL    PLANTS    TO     IMPROVE     STRAINS 

This  is  a  more  effective  method  of  improving  the  crop  than  field 
selection  as  above  described,  and  it  will  pay  the  grower  to  practice 
it.  By  continually  selecting  seed  from  individual  plants  you  are 
controlling  half  of  the  ancestry  of  your  crop.  It  is  something  like 
grading  a  herd  by  the  use  of  a  pure  bred  bull.  In  this  work  the 
standard  of  selection  may  include  other  points  besides  yield  and  height 
of  plant,  such  as  season  of  bloom,  drouth  and  disease  resistance,  etc. 
The  plant-to-row  method  should  be  used,  each  head  being  planted  in 
a  row  by  itself.  Only  the  best  rows  for  all  points  considered  should 
be  retained  for  the  improved  strain,  the  remainder  being  used  for  next 
year's  crop.  The  superior  rows  should  be  carefully  rogued  and  the 
seed  planted  in  an  increase  plot  the  following  year  and  rogued  again. 
The  third  year  there  will  be  sufficient  of  this  superior  seed  for  a  large 
acreage  and  it  should  be  worth  considerably  more  than  ordinary  seed. 


